摘要:

A study of Fallow deer (Dma dama) and Domestic dog (Canis familiaris) leads to identification of an aponeurosis in the back as an important elastic strain energy store in galloping. Kinetic energy lost by the body, as the forelegs end their backward swing and the hind legs end their forward swing, is stored briefly as elastic strain energy, and recovered in an elastic recoil. Thus energy is saved, making galloping the most economical gait for high speeds. Some strain energy is also stored in muscle fibres and in the vertebral column. Mechanical tests on the aponeurosis and vertebrae lead to estimates of the quantities of energy involved.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04944.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Miniopterus schreibersii nufalensishas a vestigial tooth on both sides of the upper jaw between the canine and following premolar. This tooth is regarded as permanent premolar P2in vestigial form.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04945.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Recent hypotheses that variation in brain size among birds and mammals result from differences in metabolic allocation during ontogeny are tested.Indices of embryonic and post‐embryonic brain growth are defined. Precocial birds and mammals have high embryonic brain growth indices which are compensated for by low post‐embryonic indices (with the exception ofHomo supiens). In contrast, altricial birds and mammals have low embryonic and high post‐embryonic indices. Altricial birds have relatively small brains at hatching and develop relatively large brains as adults, but among mammals there is no equivalent correlation between variation in adult relative brain sizes and state of neonatal development.Compensatory brain development in both birds and mammals is associated with compensatory parental metabolic allocation. In comparison with altricial development, precocial development is characterized by higher levels of brain growth and parental metabolic allocation prior to hatching or birth and lower levels subsequently. Differences between degrees of postnatal investment by the parents in the young of precocial birds versus precocial mammals may result in the different patterns of adult brain size associated with precociality versus altriciality in the two groups.The allometric exponent scaling brain on body size differs among taxonomic levels in birds. The exponent is higher for some parts of the brain than others, irrespective of taxonomic level. Unlike mammals, the exponents for birds do not show a general increase with taxonomic level. These pattcrns call into question recent interpretations of the allometric exponent in birds. and the reason for changes in exponent with taxonomic

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04946.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

A study of the dietof Sepia officinalisandS. elegansin the Ria de Vigo has shown that crustaceans are the most abundant prey in both species, followed by fish. Changes in the food composition of both species occur with growth. The type of prey eaten by the two sexes of these species is very similar. The possibility of trophic competition between juveniles of S.qficinalisandS. elegansis discussed.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04947.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Cloacal swabs from seven free‐living Grass snakes (Nutrix natrix), six adders (Vipera berus) and 17 slow‐worms (Anguis fragilis) were cultured for aerobic and anaerobic bacteria. The number of species isolated was 18, 16 and 29, respectively, and the most prevalent organisms were entero‐cocci (Grass snakes) andEscherichia coli(adders and slow‐worms). There were surprisingly few anaerobes. Bacteria with zoonotic potential includedArizona (Salmonella) arizonaefrom four slow‐worms andYersinia pseudotuberculosisfrom

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04948.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

An hitherto unpuhlicized specimen of the Javan (Sondaic) rhinoceros in the Manchester Museum is briefly described.

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04949.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

The grazing behaviour of lactating Bennett's wallabies was studied on a number of different pasture types. Increases in mean sward height resulted in a greatly reduced bite rate and an increase in the search time per bite. All wallabies showed a diurnal rhythm in grazing activity irrespective of habitat type, with least grazing activity at midday and most at night. Animals maintained on very short grass swards compensated for the reduced herbage mass by extending their grazing activity into the midday period. Lactating animals grazed for longer, had higher biting rates and a greater number of estimated bites per day than non‐lactating wallabies (17,700 vs. 7600 bites per day, respectively). In general, the response of wallabies to changes in herbage availability is similar to domestic ruminants, although wallabies may be able to graze for longer each day than ruminant

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04950.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Embryonic. foetal and placental samples were taken at hysterotomy from timed and estimated stages of pregnancy. Timed pregnancies were sampled at least every 10 days, between days 30 and 140 of the 144‐day gestationTwo placental discs of similar size were present in all cases. Placental growth followed a sigmoid curve with the most rapid growth being found between 60 and 90 days. Placentae from triplet pregnancies were larger and heavier than those from twin pregnancies. A description of the external characteristics of embryos and foetuses showed clear‐cut differences between each 10‐day interval. Foetal body weight was measured after day 70 and the body weight increased most rapidly after day 100. Twins were heavier than triplets during late pregnancy and at birth. The major organs were weighed after day 80 and the largest increase in weight gain was usually found between days 120 and 140. Fifty percent of the birth (is. 140‐day) weight was achieved by day 70–80 for the placenta and by day 120–130 for the body and organ weights. With the exception of the brain and adrenals, the body and organ weights at birth were 10–20° of their ultimate adult weight. The crown‐rump length (C.R.L.) was measured after day 50. The maximum increments in growth were found between days 70 and 110 and there was no difference between twins and triplets during pregnancy or at birth. Nineteen other trunk, limb and head measurements were taken after day 90 of pregnancy and the maximum increments in growth were found between 90 and 120 days. At birth, the trunk and limb measurements were 40° and the head was 68° of the adult size. In all weight and linear measurements, the rate of growth, which is the increment per unit of weight or length. was most rapid during the earliest ti

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04951.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Vaejovis littoralisWilliams is an intertidal scorpion inhabiting chiefly the drift zone in the high intertidal of beaches in Baja California, Mexico. Density within the drift zone averages approximately 2–4/m2(island sites) to 12/m2(mainland sites). Populations are aggregated into patches. Primarily, juveniles exhibit diurnal activity. Nocturnally active juveniles tend to be spatially segregated from nocturnally active adults within the drift zone.Diet ofV. littoralisincludes the isopodLigia, V. littoralis, spiders, pseudoscorpions, centipedes and beetles. Prey size is not a function of predator size.Centruroides exilicauda, V. littoralisandLigiawere observed as predators onV. littoralis.The adult sex ratio is skewed toward females (1 male : 2.1 females). Adult females are usually larger than adult males. Litter size ranges from 1–8. Limited data suggest that offspring size and litter size increase with maternal size.Vaejovis littoralisexhibits cryptic coloration, small size and lithophilic tarsal claws, all of which favour intertidal existence. AlthoughV. littoralisis able to withstand up to 12 hours of submergence, it does not survive submergence significantly better than a comparable desert species. Field data suggest thatV. littoralisdoes not exhibit an endogenous tidal rhy

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04952.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Hitherto uninvestigated in Hong Kong are the population dynamics, reproductive strategies and life history tactics of the Pisidiidae of which three species are known to occur locally. This study is ofMusculium lacustreinhabiting a drainage ditch of the Lam Tsuen River in the New Territories of Hong Kong and extended over 15 months during 1983–84.In Hong Kong,M. lacustreis a protandric, simultaneous hermaphrodite that matures at a length of 2 mm; the majority of each generation is, however, not mature until a length of between 4–6 mm is attained. Fertilized eggs are brooded in the inner demibranchs until they reach a length of 1.5 mm when they are released as post‐foetal larvae.Musculium lacustreis univoltine. Reproduction occurs twice a year but, sinceM. lacustveis semelparous, the population contains, at any one time, two overstepping generations. Thus, a spring generation is recruited and grows rapidly to generate a second, smaller, autumn generation. This in turn grows rapidly and matures to produce the spring generation of the succeeding year. Adult mortality occurs in late summer and winter. A few of the late‐born spring generation may overwinter to contribute to the spring generation of the succeeding year. This is not so with the autumn generation.Such sexual and life history tactics can be related to the climate and hydrology of Hong Kong and its freshwater habitats. Reproduction takes place in spring and autumn when temperatures are moderate. Mortality is high in summer and winter when the habitat is either, respectively, hot and flushed out by summer rains or cold and dry. AsM. larustreis able to overwinter but not aestivate at these latitudes (22° N), it is postulated that this holarctic species is approaching the southern limit of its asiatic range.Musculium larustreis compared with the other bivalves inhabiting fresh and brackish‐water habitats in sout

ISSN:0952-8369    

DOI:10.1111/j.1469-7998.1985.tb04953.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY